a brief overview of transition metal photoredox catalysis...

A brief overview of Transition Metal Photoredox Catalysis as a tool for organic synthesis

Literature Review PresentationDimitri Caputo

7th December 2016

1.  Introduction

2.  Photoredox catalysis

3.  Functional group interconversion

4.  C-C bond formation

5.  Conclusions

Outline

Contemporary definition

“Photoredox catalysis is a branch of catalysis that harnesses the energy of visible light to accelerate a chemical reaction via a single-electron transfer.”

- Wikipedia

“In a general sense, this approach relies on the ability of metal complexes and organic dyes to engage in single-electron transfer processes with organic substrates upon photoexcitation with visible light.”

-MacMillan

Early reports: late 1950’s

Introduction

Fe3+

Methylene blueEDTA

1,10-phenantroline

acetate buffer, pH 5visible light

Fe2+

C. K. Prier, D. A. Rankic, D. W. C. MacMillan, Chem. Rev., 2013, 113, 5322G. K. Oster, G. Oster, J. Am. Chem. Soc., 1959, 81, 5543

Contemporary definition

“Photoredox catalysis is a branch of catalysis that harnesses the energy of visible light to accelerate a chemical reaction via a single-electron transfer.”

- Wikipedia

“In a general sense, this approach relies on the ability of metal complexes and organic dyes to engage in single-electron transfer processes with organic substrates upon photoexcitation with visible light.”

-MacMillan

Early reports: late 1950’s

Introduction

Fe3+

Methylene blueEDTA

1,10-phenantroline

acetate buffer, pH 5visible light

Fe2+

C. K. Prier, D. A. Rankic, D. W. C. MacMillan, Chem. Rev., 2013, 113, 5322

Contemporary definition

“Photoredox catalysis is a branch of catalysis that harnesses the energy of visible light to accelerate a chemical reaction via a single-electron transfer.”

- Wikipedia

“In a general sense, this approach relies on the ability of metal complexes and organic dyes to engage in single-electron transfer processes with organic substrates upon photoexcitation with visible light.”

-MacMillan

Early reports: late 1950’s

Introduction

Fe3+

Methylene blueEDTA

1,10-phenantroline

acetate buffer, pH 5visible light

Fe2+

C. K. Prier, D. A. Rankic, D. W. C. MacMillan, Chem. Rev., 2013, 113, 5322G. K. Oster, G. Oster, J. Am. Chem. Soc., 1959, 81, 5543

Applications in CO2 reduction, radical polymerization initiation…

Early applications in organic chemistry:

How does it work?

Introduction

CO2

[Ru(bpy)3]Cl2[Ru(bpy)2(CO)2](PF6)2

TEOA/DMF

visible lightHCOO- EtO

OBr

Ph O OMe

Ir(ppy)3

DMF, RTvisible light

EtO

O

Ph

Br

OMeO

n

J. W. Tucker, C. R. J. Stephenson, J. Org. Chem., 2012, 77, 1617-1622H. Ishida, T. Terada, K. Tanaka, T. Tanaka, Inorg. Chem., 1990, 29, 905-911B. P. Fors, C. J. Hawker, Angew. Chem. Int. Ed., 2012, 51, 8850-8853

S+R2R1

R3 N

COOEtEtOOC [Ru(bpy)3]Cl2

25°C, room light20 min, MeCN

100%

N+

EtOOC COOEtR1 H S R3R2

Applications in CO2 reduction, radical polymerization initiation…

Early applications in organic chemistry:

How does it work?

Introduction

CO2

[Ru(bpy)3]Cl2[Ru(bpy)2(CO)2](PF6)2

TEOA/DMF

visible lightHCOO- EtO

OBr

Ph O OMe

Ir(ppy)3

DMF, RTvisible light

EtO

O

Ph

Br

OMeO

n

J. W. Tucker, C. R. J. Stephenson, J. Org. Chem., 2012, 77, 1617-1622H. Ishida, T. Terada, K. Tanaka, T. Tanaka, Inorg. Chem., 1990, 29, 905-911B. P. Fors, C. J. Hawker, Angew. Chem. Int. Ed., 2012, 51, 8850-8853

S+R2R1

R3 N

COOEtEtOOC [Ru(bpy)3]Cl2

25°C, room light20 min, MeCN

100%

N+

EtOOC COOEtR1 H S R3R2

Publications in the field: exponential increase since 2008

Citation report from Web Of ScienceTM, Basic search by topic with “photoredox”, 23rd November 2016

Applications in CO2 reduction, radical polymerization initiation…

Early applications in organic chemistry:

How does it work?

Introduction

CO2

[Ru(bpy)3]Cl2[Ru(bpy)2(CO)2](PF6)2

TEOA/DMF

visible lightHCOO- EtO

OBr

Ph O OMe

Ir(ppy)3

DMF, RTvisible light

EtO

O

Ph

Br

OMeO

n

J. W. Tucker, C. R. J. Stephenson, J. Org. Chem., 2012, 77, 1617-1622H. Ishida, T. Terada, K. Tanaka, T. Tanaka, Inorg. Chem., 1990, 29, 905-911B. P. Fors, C. J. Hawker, Angew. Chem. Int. Ed., 2012, 51, 8850-8853

S+R2R1

R3 N

COOEtEtOOC [Ru(bpy)3]Cl2

25°C, room light20 min, MeCN

100%

N+

EtOOC COOEtR1 H S R3R2

Photoredox catalysis: general process

“Transition metal mediated photoredox catalysis”, S. Crossley, Shenvi Lab Group Meeting, 14/09/2015J. W. Tucker, C. R. J. Stephenson, J. Org. Chem., 2012, 77, 1617-1622

C. K. Prier, D. A. Rankic, D. W. C. MacMillan, Chem. Rev., 2013, 113, 5322

P P*hν

D

A

ET

P D

P A

S

S

P DS

P AS

ET

ET

P DS

P AS

reductive quenching

oxidative quenching

P = photocatalyst, photoredox catalystD = electron donor species (amine, alcohol, thiol, electron-rich arene…)

A = electron acceptor species (carbonyl, halide, electron-poor arene)S = Redox neutral substrate

P

P*

P* P

PA A

D D

Photoredox catalysis: general process

“Transition metal mediated photoredox catalysis”, S. Crossley, Shenvi Lab Group Meeting, 14/09/2015J. W. Tucker, C. R. J. Stephenson, J. Org. Chem., 2012, 77, 1617-1622

C. K. Prier, D. A. Rankic, D. W. C. MacMillan, Chem. Rev., 2013, 113, 5322

P P*hν

D

A

ET

P D

P A

S

S

P DS

P AS

ET

ET

P DS

P AS

reductive quenching

oxidative quenching

P = photocatalyst, photoredox catalystD = electron donor species (amine, alcohol, thiol, electron-rich arene…)

A = electron acceptor species (carbonyl, halide, electron-poor arene)S = Redox neutral substrate

P

P*

P* P

PA A

D D

Photoredox catalysis: what about the catalyst?

Ru

NN

NN

N

N

2 Cl-

O

O

O

Br

HOBr Br

OH

Br

Metal-ligand complex Organic dye

http://www.shsu.edu/~chm_tgc/chemilumdir/JABLON.GIF

TM Photoredox catalysis: metals and ligands

“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015

Mostly Ru2+ and Ir3+

Electronic configuration

Ru2+: [Kr]3f144d6 Ir3+: [Xe]4f145d6

d6 complexes

Ligand field theory:

d orbitals

x L

Ligand field stabilisation engery

eg

t2g

Octahedral complexeslow-spin d6 state

substitutionally inert

Mn+ MLxn+

TM Photoredox catalysis: metals and ligands

“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015

Mostly Ru2+ and Ir3+

Electronic configuration

Ru2+: [Kr]3f144d6 Ir3+: [Xe]4f145d6

d6 complexes

Ligand field theory:

d orbitals

x L

Ligand field stabilisation engery

eg

t2g

Octahedral complexeslow-spin d6 state

substitutionally inert

Mn+ MLxn+

TM Photoredox catalysis: metals and ligands

“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015

Mostly Ru2+ and Ir3+

Electronic configuration

Ru2+: [Kr]3f144d6 Ir3+: [Xe]4f145d6

d6 complexes

Ligand field theory:

d orbitals

x L

Ligand field stabilisation engery

eg

t2g

Octahedral complexeslow-spin d6 state

substitutionally inert

Mn+ MLxn+

TM Photoredox catalysis: intrinsic properties of metal

“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015“Chemistry: Principles, Patterns, and Applications”, Chapter 23, B. A. Averill, P. Eldredge,

RuII

NN

NN

N

N

Ru(bpy)32+

IrIII

NN

NN

N

N

Ir(bpy)33+

Ru(II)*/Ru(III) = − 0.81 VRu(II)*/Ru(I) = 0.77 V

Ir(III)*/Ir(IV) = − 0.88 VIr(III)*/Ir(II) = 1.81 V

Similar reducing properties

Ir complex stronger oxidant than Ru complex

(same set of ligand)

RuN

N

NN

NN N

N

N

N

NN

2+

Ru

N

N

N

N

N

NN

N

N

N

N

N

2+

RuN

N

NN

NN

2+

RuN

N

NN

NN

2+

IrNN

N

F F

F

FF

F

IrNN

NN

F F

F

F

CF3

F3C

tBu

tBu

3+

3+

1+

IrNN

NN

tBu

tBu

3+

IrNN

N

3+

NMe

Me

Me

Me

ClO4-

O

BF4-O O

CO2H

HOBr

Br

Br

Br

Eosin Y

Et (S*/S )Eo (S/S )

0.79V-1.06V

lmax 539 nm

O O

CO2H

HO

Fluorescein

Et (S*/S )Eo (S/S )

0.78V-1.27V

lmax 528 nm

lmax 443 nm

Ru(bpz)32+ = Ru(II)Ru(II)*/Ru(I) = 1.45V

Ru(II)*/Ru(III) = -0.26VRu(II)/Ru(I) = -0.80VRu(III)/Ru(II) = 1.86V

2+ 2+ 2+

Ru(bpm)32+ = Ru(II)Ru(II)*/Ru(I) = 0.99V

Ru(II)*/Ru(III) = -0.21VRu(II)/Ru(I) = -0.91VRu(III)/Ru(II) = 1.69V

Ru(bpy)32+ = Ru(II)Ru(II)*/Ru(I) = 0.77V

Ru(II)*/Ru(III) = -0.81VRu(II)/Ru(I) = -1.33VRu(III)/Ru(II) = 1.29V

Ru(phen)32+ = Ru(II)Ru(II)*/Ru(I) = 0.82V

Ru(II)*/Ru(III) = -0.87VRu(II)/Ru(I) = -1.36VRu(III)/Ru(II) = 1.26V

2+

f ac-Ir(dF-ppy)33+ = Ir(III)Ir(III)/Ir(II) = -2.11VIr(IV)/Ir(III) = 1.18V

Ir(dF-CF3-ppy)2(dtbpy)3+ = Ir(III)Ir(III)*/Ir(II) = 1.21V

Ir(III)*/Ir(IV) = -0.89VIr(III)/Ir(II) = -1.37VIr(IV)/Ir(III) = 1.69V

Ir(ppy)2(dtbpy)3+ = Ir(III)Ir(III)*/Ir(II) = 0.66V

Ir(III)*/Ir(IV) = -0.96VIr(III)/Ir(II) = -1.51VIr(IV)/Ir(III) = 1.21V

f ac-Ir(ppy)33+ = Ir(III)Ir(III)*/Ir(II) = 0.31V

Ir(III)*/Ir(IV) = -1.73VIr(III)/Ir(II) = -2.19VIr(IV)/Ir(III) = 0.77V

lmax 380 nm

lmax 454 nm

lmax 422 nm lmax 375 nm

lmax 347 nm

lmax 380 nm

lmax 452 nm

lmax 430 nm

lmax 417 nm

Et (S*/S )Eo (S/S )

2.3V (T1)-0.35 V

1+

1+

Et (S*/S )Eo (S/S )

2.06V-0.57V

Mes-Acr+

Triphenylpyrylium

E* (V vs SCE))

+2.5 05.0+0.1+5.1+0.2+

Me

Me

Me

OMe HN

2.30V

Me

2.28V

1.21V1.76V

0.96

0.98V

NH2

Me

O

-O1.24V

PhMe

1.60V

1.81V

Et3N

S2.15V

MeS

1.63V

Ph

-2.5-0.5 0.2-5.1-0.1-0

IrNN

N

3+

f ac-Ir(ppy)33+ = Ir(III)Ir(III)*/Ir(II) = 0.31V

Ir(III)*/Ir(IV) = -1.73VIr(III)/Ir(II) = -2.19VIr(IV)/Ir(III) = 0.77Vlmax 375 nm

IrNN

N

F F

F

FF

F

3+

f ac-Ir(dF-ppy)33+ = Ir(III)Ir(III)/Ir(II) = -2.11VIr(IV)/Ir(III) = 1.18V

lmax 347 nm

1+

IrNN

NN

tBu

tBu

3+

Ir(ppy)2(dtbpy)3+ = Ir(III)Ir(III)*/Ir(II) = 0.66V

Ir(III)*/Ir(IV) = -0.96VIr(III)/Ir(II) = -1.51VIr(IV)/Ir(III) = 1.21Vlmax 380 nm

1+

RuN

N

NN

NN

2+

Ru(phen)32+ = Ru(II)Ru(II)*/Ru(I) = 0.82V

Ru(II)*/Ru(III) = -0.87VRu(II)/Ru(I) = -1.36VRu(III)/Ru(II) = 1.26V

2+

lmax 422 nm

IrNN

NN

F F

F

F

CF3

F3C

tBu

tBu

3+

1+

Ir(dF-CF3-ppy)2(dtbpy)3+ = Ir(III)Ir(III)*/Ir(II) = 1.21V

Ir(III)*/Ir(IV) = -0.89VIr(III)/Ir(II) = -1.37VIr(IV)/Ir(III) = 1.69V

lmax 380 nm

RuN

N

NN

NN

2+

2+

Ru(bpy)32+ = Ru(II)Ru(II)*/Ru(I) = 0.77V

Ru(II)*/Ru(III) = -0.81VRu(II)/Ru(I) = -1.33VRu(III)/Ru(II) = 1.29V

lmax 452 nm

O O

CO2H

HO

Fluorescein

Et (S*/S )Eo (S/S )

0.78V-1.27V

lmax 528 nm

O O

CO2H

HOBr

Br

Br

Br

Eosin Y

Et (S*/S )Eo (S/S )

0.79V-1.06V

lmax 539 nm

Ru

N

N

N

N

N

NN

N

N

N

N

N

2+

2+

Ru(bpm)32+ = Ru(II)Ru(II)*/Ru(I) = 0.99V

Ru(II)*/Ru(III) = -0.21VRu(II)/Ru(I) = -0.91VRu(III)/Ru(II) = 1.69V

lmax 454 nm

RuN

N

NN

NN N

N

N

N

NN

2+

lmax 443 nm

Ru(bpz)32+ = Ru(II)Ru(II)*/Ru(I) = 1.45V

Ru(II)*/Ru(III) = -0.26VRu(II)/Ru(I) = -0.80VRu(III)/Ru(II) = 1.86V

2+

NMe

Me

Me

Me

ClO4-

lmax 430 nm

Et (S*/S )Eo (S/S )

2.06V-0.57V

Mes-Acr+

O

BF4-

lmax 417 nm

Et (S*/S )Eo (S/S )

2.3V (T1)-0.35 V

Triphenylpyrylium

N

N

-2.08V

Ph

O

Me-2.14V

Ph

O

H-1.93V

Ph

O

OH-2.24V

OO

-0.45V

I

-1.16V

Br

-1.76V Cl

-2.09V

OO

O-0.85V

NO

-2.30V

N3

O2N-0.83V

F3C SO

OCl

-0.18V

-1.22V

CF3I

E* (V vs SCE))

I

-2.33V-1.71V

Ph Br

Ph

OBr

-0.49V

Electrochemical Series of Photocatalysts and Common Organic Compounds

Excited State Oxidations Reduced State Reductions

compiled by D. DiRocco 2014

TBPA = 1.05V

O

O

CN

CN

Cl

Cl

DDQ = 0.53V

N

Br

Br

Br

CAN = 0.96V(NH4)2[Ce(NO3)6]persulfate= 2.36V

SO4

persulfate = 1.85V

S2O8F FFluorine = 2.62V

H2O2hydrogen peroxide = 1.45V

MnO4permanganate = 1.43V

O O

oxygen = 0.99V

Agsilver(I) = 0.6V

Sm(II)I2 = -1.65V

Copper(II)= 0.28V

Hypochlorite = 1.39VHOCl Irono = -0.65V Zinco = -1.00V

Magnesiumo = -2.62V

Sodiumo = -2.95V

Lithiumo = -3.28V(2e-)

(2e-)

(2e-)

(2e-)

(1e-)

(4e-)

(2e-)

(2e-) (2e-) (4e-)

ascorbic acid = -0.19V

dithionite = -0.77VS2O42-

(2e-)

O

OHHO

O

OHHO

H

Common Oxidizing Agents Common Reducing Agents

TM Photoredox catalysis: metals and ligands

RuII

NN

NN

N

NRuII

N

N

NN

NNN

N

NN

NN

RuII

N

N

N

N

N

NN

N

NN

NNRuII

NN

NN

N

N

IrIIIN

N

NIrIII

N

N

NIrIII

N

NN

NIrIII

N

NN

N

F

F

F

F

F

F

F

F

FF

tBu

tBu tBu

tBu

Ru(bpy)32+ Ru(bpz)32+ Ru(bpm)32+ Ru(phen)32+

fac-Ir(ppy)3 fac-Ir(dF-ppy)3 Ir(dF-CF3-ppy)2(dtbpy)+ Ir(ppy)2(dtbpy)+

CF3

F3C

TM Photoredox catalysis: metals and ligands

RuII

NN

NN

N

NRuII

N

N

NN

NNN

N

NN

NN

RuII

N

N

N

N

N

NN

N

NN

NNRuII

NN

NN

N

N

IrIIIN

N

NIrIII

N

N

NIrIII

N

NN

NIrIII

N

NN

N

F

F

F

F

F

F

F

F

FF

tBu

tBu tBu

tBu

Ru(bpy)32+ Ru(bpz)32+ Ru(bpm)32+ Ru(phen)32+

fac-Ir(ppy)3 fac-Ir(dF-ppy)3 Ir(dF-CF3-ppy)2(dtbpy)+ Ir(ppy)2(dtbpy)+

CF3

F3C

TM Photoredox catalysis: metals and ligands

Ru complexes: homoleptic Ir complexes: homoleptic

and heteroleptic

RuII

NN

NN

N

NRuII

N

N

NN

NNN

N

NN

NN

RuII

N

N

N

N

N

NN

N

NN

NNRuII

NN

NN

N

N

IrIIIN

N

NIrIII

N

N

NIrIII

N

NN

NIrIII

N

NN

N

F

F

F

F

F

F

F

F

FF

tBu

tBu tBu

tBu

Ru(bpy)32+ Ru(bpz)32+ Ru(bpm)32+ Ru(phen)32+

fac-Ir(ppy)3 fac-Ir(dF-ppy)3 Ir(dF-CF3-ppy)2(dtbpy)+ Ir(ppy)2(dtbpy)+

CF3

F3C

TM Photoredox catalysis: usual ligand type

N

N

N

Type bpy neutral

LL

Type ppy anionic

LX

Strong e- donation Found in Ir3+ (better stabilisation)

Found in Ru2+

“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015E. Y. Li, Y.-M. Cheng, C.-C. Hsu, P.-T. Chou, G.-H. Lee, Inorg. Chem., 2006, 45, 9631

P. G. Bomben, K. C. D. Robson, P. A. Sedach, C. P. Berlinguette, Inorg. Chem., 2009, 48, 9631

Heteroleptic complexes: Spin-Orbit coupling disrupted, MLCT less efficient SO (Ir) > SO (Ru) è compensation

Ru complexes mostly homoleptic and LL ligands

TM Photoredox catalysis: usual ligand type

N

N

N

Type bpy neutral

LL

Type ppy anionic

LX

Strong e- donation Found in Ir3+ (better stabilisation)

Found in Ru2+

“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015E. Y. Li, Y.-M. Cheng, C.-C. Hsu, P.-T. Chou, G.-H. Lee, Inorg. Chem., 2006, 45, 9631

P. G. Bomben, K. C. D. Robson, P. A. Sedach, C. P. Berlinguette, Inorg. Chem., 2009, 48, 9631

Heteroleptic complexes: Spin-Orbit coupling disrupted, MLCT less efficient SO (Ir) > SO (Ru) è compensation

Ru complexes mostly homoleptic and LL ligands

TM Photoredox catalysis: usual ligand type

N

N

N

Type bpy neutral

LL

Type ppy anionic

LX

Strong e- donation Found in Ir3+ (better stabilisation)

Found in Ru2+

“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015E. Y. Li, Y.-M. Cheng, C.-C. Hsu, P.-T. Chou, G.-H. Lee, Inorg. Chem., 2006, 45, 9631

P. G. Bomben, K. C. D. Robson, P. A. Sedach, C. P. Berlinguette, Inorg. Chem., 2009, 48, 9631

Heteroleptic complexes: Spin-Orbit coupling disrupted, MLCT less efficient SO (Ir) > SO (Ru) è compensation

Ru complexes mostly homoleptic and LL ligands

TM Photoredox catalysis: usual ligand type

N

N

N

Type bpy neutral

LL

Type ppy anionic

LX

Strong e- donation Found in Ir3+ (better stabilisation)

Found in Ru2+

“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015E. Y. Li, Y.-M. Cheng, C.-C. Hsu, P.-T. Chou, G.-H. Lee, Inorg. Chem., 2006, 45, 9631

P. G. Bomben, K. C. D. Robson, P. A. Sedach, C. P. Berlinguette, Inorg. Chem., 2009, 48, 9631

Heteroleptic complexes: Spin-Orbit coupling disrupted, MLCT less efficient SO (Ir) > SO (Ru) è compensation

Ru complexes mostly homoleptic and LL ligands

TM Photoredox catalysis: heteroleptic VS homoleptic

“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015A. B. Tamayo et al., J. Am. Chem. Soc., 2003, 125, 7377-7387

M. S. Lowry et al., Chem. Mater., 2005, 17, 5712-5719

Heteroleptic: spatial modification of HOMO/LUMO

IrIII

N

NN

IrIII

N

NN

N

tBu

tBu

IrIII

N

NN

IrIII

N

NN

N

tBu

tBu

Ir(ppy)3*

Ir(ppy)2(dtbbpy)*

HOMO LUMO

TM Photoredox catalysis: heteroleptic VS homoleptic

“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015A. B. Tamayo et al., J. Am. Chem. Soc., 2003, 125, 7377-7387

M. S. Lowry et al., Chem. Mater., 2005, 17, 5712-5719

Heteroleptic: spatial modification of HOMO/LUMO

IrIII

N

NN

IrIII

N

NN

N

tBu

tBu

IrIII

N

NN

IrIII

N

NN

N

tBu

tBu

Ir(ppy)3*

Ir(ppy)2(dtbbpy)*

HOMO LUMO

TM Photoredox catalysis: effects of ligand on redox potentials

“Electrochemical Series of Photocatalysts and Common Organic Coumpounds”, D. DiRocco, 2014, Merck“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015

IrIIIN

N

NIrIII

N

NN

NIrIII

N

NN

N

F

F

FF

tBu

tButBu

tBu

fac-Ir(ppy)3 Ir(dF-CF3-ppy)2(dtbpy)+Ir(ppy)2(dtbpy)+

CF3

F3C

Ir(III)*/Ir(IV) = − 1.73 VIr(III)*/Ir(II) = 0.31 V

Ir(III)*/Ir(IV) = − 0.96 VIr(III)*/Ir(II) = 0.66 V

Ir(III)*/Ir(IV) = − 0.89 VIr(III)*/Ir(II) = 1.21 V

IrIIIN

N

NIrIII

N

NN

NIrIII

N

NN

N

F

F

FF

tBu

tButBu

tBu

fac-Ir(ppy)3 Ir(dF-CF3-ppy)2(dtbpy)+Ir(ppy)2(dtbpy)+

CF3

F3C

Ir(III)*/Ir(IV) = − 1.73 VIr(III)*/Ir(II) = 0.31 V

Ir(III)*/Ir(IV) = − 0.96 VIr(III)*/Ir(II) = 0.66 V

Ir(III)*/Ir(IV) = − 0.89 VIr(III)*/Ir(II) = 1.21 V

TM Photoredox catalysis: effects of ligand on redox potentials

LL to LX ligand: electron density on the metal increases è Reductive power increases

“Electrochemical Series of Photocatalysts and Common Organic Coumpounds”, D. DiRocco, 2014, Merck“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015

IrIIIN

N

NIrIII

N

NN

NIrIII

N

NN

N

F

F

FF

tBu

tButBu

tBu

fac-Ir(ppy)3 Ir(dF-CF3-ppy)2(dtbpy)+Ir(ppy)2(dtbpy)+

CF3

F3C

Ir(III)*/Ir(IV) = − 1.73 VIr(III)*/Ir(II) = 0.31 V

Ir(III)*/Ir(IV) = − 0.96 VIr(III)*/Ir(II) = 0.66 V

Ir(III)*/Ir(IV) = − 0.89 VIr(III)*/Ir(II) = 1.21 V

TM Photoredox catalysis: effects of ligand on redox potentials

LL to LX ligand: electron density on the metal increases è Reductive power increases EWG on ligands: electron density on the metal decreases è Oxidative power increases

“Electrochemical Series of Photocatalysts and Common Organic Coumpounds”, D. DiRocco, 2014, Merck“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015

IrIIIN

N

NIrIII

N

NN

NIrIII

N

NN

N

F

F

FF

tBu

tButBu

tBu

fac-Ir(ppy)3 Ir(dF-CF3-ppy)2(dtbpy)+Ir(ppy)2(dtbpy)+

CF3

F3C

Ir(III)*/Ir(IV) = − 1.73 VIr(III)*/Ir(II) = 0.31 V

Ir(III)*/Ir(IV) = − 0.96 VIr(III)*/Ir(II) = 0.66 V

Ir(III)*/Ir(IV) = − 0.89 VIr(III)*/Ir(II) = 1.21 V

TM Photoredox catalysis: effects of ligand on redox potentials

LL to LX ligand: electron density on the metal increases è Reductive power increases EWG on ligands: electron density on the metal decreases è Oxidative power increases

TM/ligand complexes = tunable catalysts

“Electrochemical Series of Photocatalysts and Common Organic Coumpounds”, D. DiRocco, 2014, Merck“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015

Photoredox catalysis: active species

C. K. Prier, D. A. Rankic, D. W. C. MacMillan, Chem. Rev., 2013, 113, 5322-5363“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015

N. H. Damrauer, G. Cerullo, A. Yeh, T. R. Boussie, C. V. Shank, J. K. McCusker, Science, 1997, 275, 54-57

τ(1MLCT) < τ(3MLCT)

3MLCT active species = P*

[Ru(bpy)3]Cl2octahedral, d6

low-spin configuration(substitutionally inert)

λmax = 452 nm

RuII

NN

NN

N

N

2 Cl-

eg*

π*

t2g*

RuIII

NN

NN

N

N

2 Cl-

eg*

π*

t2g*

Ground state Excited singlet state 1MLCTτ = 100-300 10-15 s

RuIII

NN

NN

N

N

2 Cl-

eg*

π*

t2g*

Excited triplet state 3MLCTτ = 1100 10-9 s

Photon absorption

MLCT

ISC

Photoredox catalysis: active species

C. K. Prier, D. A. Rankic, D. W. C. MacMillan, Chem. Rev., 2013, 113, 5322-5363“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015

N. H. Damrauer, G. Cerullo, A. Yeh, T. R. Boussie, C. V. Shank, J. K. McCusker, Science, 1997, 275, 54-57

τ(1MLCT) < τ(3MLCT)

3MLCT active species = P*

[Ru(bpy)3]Cl2octahedral, d6

low-spin configuration(substitutionally inert)

λmax = 452 nm

RuII

NN

NN

N

N

2 Cl-

eg*

π*

t2g*

RuIII

NN

NN

N

N

2 Cl-

eg*

π*

t2g*

Ground state Excited singlet state 1MLCTτ = 100-300 10-15 s

RuIII

NN

NN

N

N

2 Cl-

eg*

π*

t2g*

Excited triplet state 3MLCTτ = 1100 10-9 s

Photon absorption

MLCT

ISC

Photoredox catalysis: active species

C. K. Prier, D. A. Rankic, D. W. C. MacMillan, Chem. Rev., 2013, 113, 5322-5363“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015

N. H. Damrauer, G. Cerullo, A. Yeh, T. R. Boussie, C. V. Shank, J. K. McCusker, Science, 1997, 275, 54-57

τ(1MLCT) < τ(3MLCT)

3MLCT active species = P*

[Ru(bpy)3]Cl2octahedral, d6

low-spin configuration(substitutionally inert)

λmax = 452 nm

RuII

NN

NN

N

N

2 Cl-

eg*

π*

t2g*

RuIII

NN

NN

N

N

2 Cl-

eg*

π*

t2g*

Ground state Excited singlet state 1MLCTτ = 100-300 10-15 s

RuIII

NN

NN

N

N

2 Cl-

eg*

π*

t2g*

Excited triplet state 3MLCTτ = 1100 10-9 s

Photon absorption

MLCT

ISC

Photoredox catalysis: active species

C. K. Prier, D. A. Rankic, D. W. C. MacMillan, Chem. Rev., 2013, 113, 5322-5363“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015

N. H. Damrauer, G. Cerullo, A. Yeh, T. R. Boussie, C. V. Shank, J. K. McCusker, Science, 1997, 275, 54-57

τ(1MLCT) < τ(3MLCT)

3MLCT active species = P*

[Ru(bpy)3]Cl2octahedral, d6

low-spin configuration(substitutionally inert)

λmax = 452 nm

RuII

NN

NN

N

N

2 Cl-

eg*

π*

t2g*

RuIII

NN

NN

N

N

2 Cl-

eg*

π*

t2g*

Ground state Excited singlet state 1MLCTτ = 100-300 10-15 s

RuIII

NN

NN

N

N

2 Cl-

eg*

π*

t2g*

Excited triplet state 3MLCTτ = 1100 10-9 s

Photon absorption

MLCT

ISC

Photoredox catalysis: active species

C. K. Prier, D. A. Rankic, D. W. C. MacMillan, Chem. Rev., 2013, 113, 5322-5363“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015

N. H. Damrauer, G. Cerullo, A. Yeh, T. R. Boussie, C. V. Shank, J. K. McCusker, Science, 1997, 275, 54-57

τ(1MLCT) < τ(3MLCT)

3MLCT active species = P*

[Ru(bpy)3]Cl2octahedral, d6

low-spin configuration(substitutionally inert)

λmax = 452 nm

RuII

NN

NN

N

N

2 Cl-

eg*

π*

t2g*

RuIII

NN

NN

N

N

2 Cl-

eg*

π*

t2g*

Ground state Excited singlet state 1MLCTτ = 100-300 10-15 s

RuIII

NN

NN

N

N

2 Cl-

eg*

π*

t2g*

Excited triplet state 3MLCTτ = 1100 10-9 s

Photon absorption

MLCT

ISC

Photoredox catalysis: Thermodynamics and kinetics

“Behind the scenes with Transition Metal Photocatalysts”, E. R. Welin, MacMillan Group Meetings, 12/02/2015C. K. Prier, D. A. Rankic, D. W. C. MacMillan, Chem. Rev., 2013, 113, 5322-5363

J. W. Tucker, C. R. J. Stephenson, J. Org. Chem., 2012, 77, 1617-1622

Ru(bpy)32+

1Ru*(bpy)32+

3Ru*(bpy)32+

Ru(bpy)3+ Ru(bpy)33+

hν

ISCRu*(II)/Ru(I) = 0.77 V

Ru(II)/Ru(I) = -1.33 V Ru(III)/Ru(II) = 1.29 V

Ru(III)/Ru*(II) = -0.81 V

Reductive quenching Oxidative quenching

Ru(bpy)32+

1Ru*(bpy)32+

3Ru*(bpy)32+

Ru(bpy)3+ Ru(bpy)33+

hν

ISCRu*(II)/Ru(I) = 0.77 V

Ru(II)/Ru(I) = -1.33 V Ru(III)/Ru(II) = 1.29 V

Ru(III)/Ru*(II) = -0.81 V

Reductive quenching Oxidative quenching

Photoredox catalysis: Thermodynamics and kinetics

R. A. Marcus, J. Chem. Phys., 1956, 24, 966 A Very Brief Introduction of the Concepts of Marcus Theory, V. Shurtleff, MacMillan Group Meetings, 26/06/2016

J. W. Tucker, C. R. J. Stephenson, J. Org. Chem., 2012, 77, 1617-1622

Ru(bpy)32+

1Ru*(bpy)32+

3Ru*(bpy)32+

Ru(bpy)3+ Ru(bpy)33+

hν

ISCRu*(II)/Ru(I) = 0.77 V

Ru(II)/Ru(I) = -1.33 V Ru(III)/Ru(II) = 1.29 V

Ru(III)/Ru*(II) = -0.81 V

Reductive quenching Oxidative quenching

Photoredox catalysis: Thermodynamics and kinetics

R. A. Marcus, J. Chem. Phys., 1956, 24, 966 A Very Brief Introduction of the Concepts of Marcus Theory, V. Shurtleff, MacMillan Group Meetings, 26/06/2016

J. W. Tucker, C. R. J. Stephenson, J. Org. Chem., 2012, 77, 1617-1622

Beware of the Marcus inversion

Functional group interconversion

Reduction of electron-deficient olefins

C. Pac, M. Ihama, M. Yasuda, Y. Miyauchi, H. Sakurai, J. Am. Chem. Soc., 1981, 103, 6495-6497

CN

NC

CN

H3CO

Ph PhCN

61% 33%

33%

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

N

NH2

O

BnBNAH

N

NH2

O

Bn

COOMeMeOOC

COOMeMeOOC

MeOOC COOMe

N

NH2

O

Bn

H+, e−

−e−

MeOOC COOMeN+

NH2

O

Bn

H+

−H+

•  SM doesn’t quench *Ru(bpy)32+

è Reductive quenching •  BNAH-4,4-d2: next to no deuteration CH3OD, CD3OD: deuteration

è Direct H transfer negligeable •  Last ET from Ru(bpy)+ or BNA�

-1.33 V 0.77 V

0.76 V

-0.94 V

MeOOC COOMe

Ru(bpy)3Cl2 (2 mol%)BNAH (2.0 equiv.)

pyridine/MeOHvisible light, 96%

MeOOC

COOMe

Reduction of electron-deficient olefins

C. Pac, M. Ihama, M. Yasuda, Y. Miyauchi, H. Sakurai, J. Am. Chem. Soc., 1981, 103, 6495-6497

CN

NC

CN

H3CO

Ph PhCN

61% 33%

33%

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

N

NH2

O

BnBNAH

N

NH2

O

Bn

COOMeMeOOC

COOMeMeOOC

MeOOC COOMe

N

NH2

O

Bn

H+, e−

−e−

MeOOC COOMeN+

NH2

O

Bn

H+

−H+

•  SM doesn’t quench *Ru(bpy)32+

è Reductive quenching •  BNAH-4,4-d2: next to no deuteration CH3OD, CD3OD: deuteration

è Direct H transfer negligeable •  Last ET from Ru(bpy)+ or BNA�

-1.33 V 0.77 V

0.76 V

-0.94 V

MeOOC COOMe

Ru(bpy)3Cl2 (2 mol%)BNAH (2.0 equiv.)

pyridine/MeOHvisible light, 96%

MeOOC

COOMe

Reduction of electron-deficient olefins

C. Pac, M. Ihama, M. Yasuda, Y. Miyauchi, H. Sakurai, J. Am. Chem. Soc., 1981, 103, 6495-6497

CN

NC

CN

H3CO

Ph PhCN

61% 33%

33%

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

N

NH2

O

BnBNAH

N

NH2

O

Bn

COOMeMeOOC

COOMeMeOOC

MeOOC COOMe

N

NH2

O

Bn

H+, e−

−e−

MeOOC COOMeN+

NH2

O

Bn

H+

−H+

•  SM doesn’t quench *Ru(bpy)32+

è Reductive quenching •  BNAH-4,4-d2: next to no deuteration CH3OD, CD3OD: deuteration

è Direct H transfer negligeable •  Last ET from Ru(bpy)+ or BNA�

-1.33 V 0.77 V

0.76 V

-0.94 V

MeOOC COOMe

Ru(bpy)3Cl2 (2 mol%)BNAH (2.0 equiv.)

pyridine/MeOHvisible light, 96%

MeOOC

COOMe

Reduction of electron-deficient olefins

C. Pac, M. Ihama, M. Yasuda, Y. Miyauchi, H. Sakurai, J. Am. Chem. Soc., 1981, 103, 6495-6497

CN

NC

CN

H3CO

Ph PhCN

61% 33%

33%

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

N

NH2

O

BnBNAH

N

NH2

O

Bn

COOMeMeOOC

COOMeMeOOC

MeOOC COOMe

N

NH2

O

Bn

H+, e−

−e−

MeOOC COOMeN+

NH2

O

Bn

H+

−H+

•  SM doesn’t quench *Ru(bpy)32+

è Reductive quenching •  BNAH-4,4-d2: next to no deuteration CH3OD, CD3OD: deuteration

è Direct H transfer negligeable •  Last ET from Ru(bpy)+ or BNA�

-1.33 V 0.77 V

0.76 V

-0.94 V

MeOOC COOMe

Ru(bpy)3Cl2 (2 mol%)BNAH (2.0 equiv.)

pyridine/MeOHvisible light, 96%

MeOOC

COOMe

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

N N

BrO

Ph

H H

N+

H+

O

PhO

Ph H

Reductive dehalogenation: activated halides

S. Fukuzumi, S. Mochizuki, T. Tanaka, J. Phys. Chem., 1990, 94, 722-726 S. Fukuzumi, S. Mochizuki, K. Hironaka, T. Tanaka, J. Am. Chem. Soc., 1987, 109, 305-316

BrO

Ph

Ru(bpy)3Cl2 (5 mol%)9,10-dihydro-10-methylacridine

MeCN, visible light

O

Ph

0.77 V

0.57-0.80 V

-0.49 V

-1.33 V

•  Bromide doesn’t quench Ru(bpy)32+

è reductive quenching •  Addition of HClO4: quenching by AcrH2 decreases

è AcrH2 à AcrH3+ (weaker reductant)

•  More HClO4: increase of quenching and reaction conversion

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

N N

BrO

Ph

H H

N+

O

PhO

Ph H

Reductive dehalogenation: activated halides

S. Fukuzumi, S. Mochizuki, T. Tanaka, J. Phys. Chem., 1990, 94, 722-726 S. Fukuzumi, S. Mochizuki, K. Hironaka, T. Tanaka, J. Am. Chem. Soc., 1987, 109, 305-316

BrO

Ph

Ru(bpy)3Cl2 (5 mol%)9,10-dihydro-10-methylacridine

MeCN, visible light

O

Ph

0.77 V

0.57-0.80 V

-0.49 V

-1.33 V

•  Bromide doesn’t quench Ru(bpy)32+

è reductive quenching •  Addition of HClO4: quenching by AcrH2 decreases

è AcrH2 à AcrH3+ (weaker reductant)

•  More HClO4: increase of quenching and reaction conversion

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

N N

BrO

Ph

H H

N+

O

PhO

Ph H

Reductive dehalogenation: activated halides

S. Fukuzumi, S. Mochizuki, T. Tanaka, J. Phys. Chem., 1990, 94, 722-726 S. Fukuzumi, S. Mochizuki, K. Hironaka, T. Tanaka, J. Am. Chem. Soc., 1987, 109, 305-316

BrO

Ph

Ru(bpy)3Cl2 (5 mol%)9,10-dihydro-10-methylacridine

MeCN, visible light

O

Ph

0.77 V

0.57-0.80 V

-0.49 V

-1.33 V

•  Bromide doesn’t quench Ru(bpy)32+

è reductive quenching •  Addition of HClO4: quenching by AcrH2 decreases

è AcrH2 à AcrH3+ (weaker reductant)

•  More HClO4: increase of quenching and reaction conversion

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)33+

N

N

BrO

Ph

OH

Ph

H H

O

PhBr

N

−H+

N+

H+

Reductive dehalogenation: activated halides

S. Fukuzumi, S. Mochizuki, T. Tanaka, J. Phys. Chem., 1990, 94, 722-726 S. Fukuzumi, S. Mochizuki, K. Hironaka, T. Tanaka, J. Am. Chem. Soc., 1987, 109, 305-316

BrO

Ph

Ru(bpy)3Cl2 (5 mol%)9,10-dihydro-10-methylacridine

MeCN, visible light

O

Ph

•  Large quantities of HClO4 è induces oxidative quenching

•  Reduction of phenacyl chloride possible

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)33+

N

N

BrO

Ph

OH

Ph

H H

O

PhBr

N

−H+

N+

H+

Reductive dehalogenation: activated halides

S. Fukuzumi, S. Mochizuki, T. Tanaka, J. Phys. Chem., 1990, 94, 722-726 S. Fukuzumi, S. Mochizuki, K. Hironaka, T. Tanaka, J. Am. Chem. Soc., 1987, 109, 305-316

BrO

Ph

Ru(bpy)3Cl2 (5 mol%)9,10-dihydro-10-methylacridine

MeCN, visible light

O

Ph

•  Large quantities of HClO4 è induces oxidative quenching

•  Reduction of phenacyl chloride possible

Reductive dehalogenation: activated halides

J. M. R. Narayanam, J. W. Tucker, C. R. J. Stephenson, J. Am. Chem. Soc., 2009, 131, 8756–8757 U. Pischel et al., J. Am. Chem. Soc., 2000, 122, 2027-2043

N HHOH

O

0.68 V

0.77 V

R X

Ru(bpy)3Cl2 (2.5 mol%)i-Pr2NEt / HCOOH (10 equiv.)

ori-Pr2NEt (2.0 equiv.) / Hantzsch ester (1.1 equiv.)

DMF, rt, 4-24hvisible light

R H

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

N N

RX

R

N+

RH

H

NBoc

NCOOMe

COOMeH

H

95%

O N

Bn

O O

HPh

OH

95% from Br80% from Cl

I

O

OPh

HO

OPh

H

I O

OPh

H

88% from ClHantzsch ester

81% from ClHantzsch ester

89% from ClHantzsch ester

Reductive dehalogenation: activated halides

J. M. R. Narayanam, J. W. Tucker, C. R. J. Stephenson, J. Am. Chem. Soc., 2009, 131, 8756–8757 U. Pischel et al., J. Am. Chem. Soc., 2000, 122, 2027-2043

N HHOH

O

0.68 V

0.77 V

R X

Ru(bpy)3Cl2 (2.5 mol%)i-Pr2NEt / HCOOH (10 equiv.)

ori-Pr2NEt (2.0 equiv.) / Hantzsch ester (1.1 equiv.)

DMF, rt, 4-24hvisible light

R H

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

N N

RX

R

N+

RH

H

NBoc

NCOOMe

COOMeH

H

95%

O N

Bn

O O

HPh

OH

95% from Br80% from Cl

I

O

OPh

HO

OPh

H

I O

OPh

H

88% from ClHantzsch ester

81% from ClHantzsch ester

89% from ClHantzsch ester

Reductive dehalogenation: activated halides

J. M. R. Narayanam, J. W. Tucker, C. R. J. Stephenson, J. Am. Chem. Soc., 2009, 131, 8756–8757 U. Pischel et al., J. Am. Chem. Soc., 2000, 122, 2027-2043

N HHOH

O

0.68 V

0.77 V

R X

Ru(bpy)3Cl2 (2.5 mol%)i-Pr2NEt / HCOOH (10 equiv.)

ori-Pr2NEt (2.0 equiv.) / Hantzsch ester (1.1 equiv.)

DMF, rt, 4-24hvisible light

R H

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

N N

RX

R

N+

RH

H

NBoc

NCOOMe

COOMeH

H

95%

O N

Bn

O O

HPh

OH

95% from Br80% from Cl

I

O

OPh

HO

OPh

H

I O

OPh

H

88% from ClHantzsch ester

81% from ClHantzsch ester

89% from ClHantzsch ester

R X

Ir(ppy)3 (1.0−2.5 mol%)n-Bu3N (2−10 equiv.)

HCOOH (5−10 equiv.) or Hantzsch ester (1.1 equiv.)

DMF , 2.5−60hvisible light

R H

Reductive dehalogenation: unactivated iodides

J. D. Nguyen, E. M. D’Amato, J. M. R. Narayanam, C. R. J. Stephenson, Nature Chem., 2012, 4, 854–859

H

BnO 4

95%

N H5

85%

O

O

O

O

OH

H

MeOOC NH2

H83% 93%

Use of Ir(ppy)3: better reducing power E = -1.73 V

-1.59 V < E (iodobenzene) < -2.24 V

R X

Ir(ppy)3 (1.0−2.5 mol%)n-Bu3N (2−10 equiv.)

HCOOH (5−10 equiv.) or Hantzsch ester (1.1 equiv.)

DMF , 2.5−60hvisible light

R H

Reductive dehalogenation: unactivated iodides

J. D. Nguyen, E. M. D’Amato, J. M. R. Narayanam, C. R. J. Stephenson, Nature Chem., 2012, 4, 854–859

H

BnO 4

95%

N H5

85%

O

O

O

O

OH

H

MeOOC NH2

H83% 93%

Use of Ir(ppy)3: better reducing power E = -1.73 V

-1.59 V < E (iodobenzene) < -2.24 V

Reduction of hydrazides and hydrazines

M. Zhu, N. Zheng, Synthesis, 2011, 14, 2223-2236

Ru*(II)/Ru(I) = 1.45 V

RuII

N

N

NN

NNN

N

NN

NN

Ph N

OPh

NH2

N Ph

NH2

Ru(bpz)3(PF6)2 (2 mol%)

MeCN/MeOH, 24-48hair, visible light

Ph NH

OPh

NH

Ph

74%

83%

Ru(bpz)32+

*Ru(bpz)32+ Ru(bpz)3+

N NH2R

PhN NH2R

Ph

−H+N NHR

Ph

N NR

PhO O

H

N NR

PhO OH N NR

PhO

OH

NR

Ph

O2

NR

Ph

H+NR

Ph

H

Reduction of hydrazides and hydrazines

M. Zhu, N. Zheng, Synthesis, 2011, 14, 2223-2236

Ru*(II)/Ru(I) = 1.45 V

RuII

N

N

NN

NNN

N

NN

NN

Ph N

OPh

NH2

N Ph

NH2

Ru(bpz)3(PF6)2 (2 mol%)

MeCN/MeOH, 24-48hair, visible light

Ph NH

OPh

NH

Ph

74%

83%

Ru(bpz)32+

*Ru(bpz)32+ Ru(bpz)3+

N NH2R

PhN NH2R

Ph

−H+N NHR

Ph

N NR

PhO O

H

N NR

PhO OH N NR

PhO

OH

NR

Ph

O2

NR

Ph

H+NR

Ph

H

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

i-Pr2NEt

ArN3

ArN3 Ar

NN+N

H

ArNN+N

H

ArNH

H+

ArNH

H

i-Pr2NEt

NEt

i-Pr2NEt

Reduction of azides

Y. Chen, A. S. Kamlet, J. B. Steinman, D. R. Liu, Nature Chem., 2011, 3, 146-153

N3

R

Ru(bpy)3Cl2 (5 mol%)i-PrNEt2/HCOOH (10 equiv.)Hantzsch ester (1.5 equiv.)

CH2Cl2, rt, 2hvisible light

NH2

R

•  Work in aqueous media, linked with DNA, sugars •  Chemoselective: inert to halides, mesylates, aldehydes, free hydroxyl, carboxylic acids, amides, alkenes, alkynes

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

i-Pr2NEt

ArN3

ArN3 Ar

NN+N

H

ArNN+N

H

ArNH

H+

ArNH

H

i-Pr2NEt

NEt

i-Pr2NEt

Reduction of azides

Y. Chen, A. S. Kamlet, J. B. Steinman, D. R. Liu, Nature Chem., 2011, 3, 146-153

N3

R

Ru(bpy)3Cl2 (5 mol%)i-PrNEt2/HCOOH (10 equiv.)Hantzsch ester (1.5 equiv.)

CH2Cl2, rt, 2hvisible light

NH2

R

•  Work in aqueous media, linked with DNA, sugars •  Chemoselective: inert to halides, mesylates, aldehydes, free hydroxyl, carboxylic acids, amides, alkenes, alkynes

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

i-Pr2NEt

ArN3

ArN3 Ar

NN+N

H

ArNN+N

H

ArNH

H+

ArNH

H

i-Pr2NEt

NEt

i-Pr2NEt

Reduction of azides

Y. Chen, A. S. Kamlet, J. B. Steinman, D. R. Liu, Nature Chem., 2011, 3, 146-153

N3

R

Ru(bpy)3Cl2 (5 mol%)i-PrNEt2/HCOOH (10 equiv.)Hantzsch ester (1.5 equiv.)

CH2Cl2, rt, 2hvisible light

NH2

R

•  Work in aqueous media, linked to DNA, sugars •  Chemoselective: inert to halides, mesylates, aldehydes, free hydroxyl, carboxylic acids, amides, alkenes, alkynes

Deprotection of p-Methoxybenzylether

J. W. Tucker, J. M. R. Narayanam, P. S. Shah, C. R. J. Stephenson, Chem. Commun., 2011, 47, 5040-5042

IrIII

N

NN

N

tBu

tBu

F3C F

FCF3

FF

IrL33+

*IrL33+ IrL34+

CCl3BrCCl3

R O

OMe

R O

OMe

R O

OMeCHCl3

R OH

O

H

OMe

H

O O O H6

80%a

O H

84%

Bn O O H6O H

69%

BocHN O H6

79%a92%a

- 1.21 V 1.68 V

R O

OMe

Ir(dF(CF3)ppy)2(dtbbpy)PF6 (1 mol%)BrCCl3 (2.0 equiv.)

MeCN, 12-18hblue LEDs

R OH

Deprotection of p-Methoxybenzylether

J. W. Tucker, J. M. R. Narayanam, P. S. Shah, C. R. J. Stephenson, Chem. Commun., 2011, 47, 5040-5042

IrIII

N

NN

N

tBu

tBu

F3C F

FCF3

FF

IrL33+

*IrL33+ IrL34+

CCl3BrCCl3

R O

OMe

R O

OMe

R O

OMeCHCl3

R OH

O

H

OMe

H

O O O H6

80%a

O H

84%

Bn O O H6O H

69%

BocHN O H6

79%a92%a

- 1.21 V 1.68 V

R O

OMe

Ir(dF(CF3)ppy)2(dtbbpy)PF6 (1 mol%)BrCCl3 (2.0 equiv.)

MeCN, 12-18hblue LEDs

R OH

Deprotection of p-Methoxybenzylether

J. W. Tucker, J. M. R. Narayanam, P. S. Shah, C. R. J. Stephenson, Chem. Commun., 2011, 47, 5040-5042

IrIII

N

NN

N

tBu

tBu

F3C F

FCF3

FF

IrL33+

*IrL33+ IrL34+

CCl3BrCCl3

R O

OMe

R O

OMe

R O

OMeCHCl3

R OH

O

H

OMe

H

O O O H6

80%a

O H

84%

Bn O O H6O H

69%

BocHN O H6

79%a92%a

- 1.21 V 1.68 V

R O

OMe

Ir(dF(CF3)ppy)2(dtbbpy)PF6 (1 mol%)BrCCl3 (2.0 equiv.)

MeCN, 12-18hblue LEDs

R OH

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

O2 O2

N

OMe

COORAr

N

OMe

COORAr

OMe

Ar COOR

Br

Ar COOR Ar COOR

O Br HBr

O2 O2

Ar COOR

OO2

Ru(bpy)32+

air, baseRu(bpy)3+

Aerobic oxitation of benzylic halides

Y. Su, L. Zhang, N. Jiao, Org. Lett., 2011, 13, 2168-2171

Ar COOR

Br

Ru(bpy)3Cl2 (0.5 mol%)4-methoxypyridine (20 mol%)

Li2CO3 (1.0 equiv.)

DMA, 25°C, air, 24-48h Ar COOR

O

Ph COOEt

O

75%

Cl

COOiPr

O

75%

Ph

O

O

Cl

82%from Cl

Ph Ph

O

40%2.5 equiv. of pyridine

Cs2CO3

OO

O

0%

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

O2 O2

N

OMe

COORAr

N

OMe

COORAr

OMe

Ar COOR

Br

Ar COOR Ar COOR

O Br HBr

O2 O2

Ar COOR

OO2

Ru(bpy)32+

air, baseRu(bpy)3+

Aerobic oxitation of benzylic halides

Y. Su, L. Zhang, N. Jiao, Org. Lett., 2011, 13, 2168-2171

Ar COOR

Br

Ru(bpy)3Cl2 (0.5 mol%)4-methoxypyridine (20 mol%)

Li2CO3 (1.0 equiv.)

DMA, 25°C, air, 24-48h Ar COOR

O

Ph COOEt

O

75%

Cl

COOiPr

O

75%

Ph

O

O

Cl

82%from Cl

Ph Ph

O

40%2.5 equiv. of pyridine

Cs2CO3

OO

O

0%

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

O2 O2

N

OMe

COORAr

N

OMe

COORAr

OMe

Ar COOR

Br

Ar COOR Ar COOR

O Br HBr

O2 O2

Ar COOR

OO2

Ru(bpy)32+

air, baseRu(bpy)3+

Aerobic oxitation of benzylic halides

Y. Su, L. Zhang, N. Jiao, Org. Lett., 2011, 13, 2168-2171

Ar COOR

Br

Ru(bpy)3Cl2 (0.5 mol%)4-methoxypyridine (20 mol%)

Li2CO3 (1.0 equiv.)

DMA, 25°C, air, 24-48h Ar COOR

O

Ph COOEt

O

75%

Cl

COOiPr

O

75%

Ph

O

O

Cl

82%from Cl

Ph Ph

O

40%2.5 equiv. of pyridine

Cs2CO3

OO

O

0%

C-C Bond Formation

Reductive radical cyclization

J. W. Tucker, J. D. Nguyen, J. M. R. Narayanam, S. W. Krabbe, C. R. J. Stephenson, Chem. Commun, 2010, 46, 4985-4987

BrMeOOC COOMe Ru(bpy)3Cl2 (1 mol%)Et3N (2.0 equiv.)

DMF, blue LEDs69%

MeOOC COOMe

Br BrOH

Ir(ppy)2(dtbbpy)PF6(1 mol%)

OH

Br

85%

Br

NO

NO

73%

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

N N

BrMeOOC COOMe

MeOOC COOMeCOOMe

MeOOC

COOMeMeOOC

COOMeMeOOC

Reductive radical cyclization

J. W. Tucker, J. D. Nguyen, J. M. R. Narayanam, S. W. Krabbe, C. R. J. Stephenson, Chem. Commun, 2010, 46, 4985-4987

BrMeOOC COOMe Ru(bpy)3Cl2 (1 mol%)Et3N (2.0 equiv.)

DMF, blue LEDs69%

MeOOC COOMe

Br BrOH

Ir(ppy)2(dtbbpy)PF6(1 mol%)

OH

Br

85%

Br

NO

NO

73%

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

N N

BrMeOOC COOMe

MeOOC COOMeCOOMe

MeOOC

COOMeMeOOC

COOMeMeOOC

Br BrOH

Ir(ppy)2(dtbbpy)PF6(1 mol%)

OH

Br

85%

Br

NO

NO

73%

BrMeOOC COOMe Ru(bpy)3Cl2 (1 mol%)Et3N (2.0 equiv.)

DMF, blue LEDs69%

MeOOC COOMe

Reductive radical cyclization

J. W. Tucker, J. D. Nguyen, J. M. R. Narayanam, S. W. Krabbe, C. R. J. Stephenson, Chem. Commun, 2010, 46, 4985-4987

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)3+

N N

BrMeOOC COOMe

MeOOC COOMeCOOMe

MeOOC

COOMeMeOOC

COOMeMeOOC

Atom Transfer Radical Addition

J. W. Tucker, J. D. Nguyen, J. M. R. Narayanam, S. W. Krabbe, C. R. J. Stephenson, Chem. Commun, 2010, 46, 4985-4987

R X R' R''

Ru(bpy)3Cl2 (1.0 mol%)10 mol% LiBr

DMSO, visible light R'

R R''

X

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)33+

R X R X

R'R

R'

R'RLiX

R X

R'R

R'R

X

X

Radical-polar crossover

Radical propagation

NHBoc NHBocBr

EtO2C

EtO2C

BrEtO2CFF

CO2Et CO2Et

IF3C

99%

88%

90%

Atom Transfer Radical Addition

J. W. Tucker, J. D. Nguyen, J. M. R. Narayanam, S. W. Krabbe, C. R. J. Stephenson, Chem. Commun, 2010, 46, 4985-4987

R X R' R''

Ru(bpy)3Cl2 (1.0 mol%)10 mol% LiBr

DMSO, visible light R'

R R''

X

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)33+

R X R X

R'R

R'

R'RLiX

R X

R'R

R'R

X

X

Radical-polar crossover

Radical propagation

NHBoc NHBocBr

EtO2C

EtO2C

BrEtO2CFF

CO2Et CO2Et

IF3C

99%

88%

90%

Atom Transfer Radical Addition

J. W. Tucker, J. D. Nguyen, J. M. R. Narayanam, S. W. Krabbe, C. R. J. Stephenson, Chem. Commun, 2010, 46, 4985-4987

R X R' R''

Ru(bpy)3Cl2 (1.0 mol%)10 mol% LiBr

DMSO, visible light R'

R R''

X

Ru(bpy)32+

*Ru(bpy)32+ Ru(bpy)33+

R X R X

R'R

R'

R'RLiX

R X

R'R

R'R

X

X

Radical-polar crossover

Radical propagation

NHBoc NHBocBr

EtO2C

EtO2C

BrEtO2CFF

CO2Et CO2Et

IF3C

99%

88%

90%

α-Amino C-H arylation

Nn

RX

CN

EWG

Ir(ppy)3 (1 mol%)NaOAc (2.0 equiv.)

DMA, 23°C, 12hvisible light (26W CFL)

Nn

R

XEWG

Nn

RIr(ppy)3

*Ir(ppy)3 Ir(ppy)3+

XEWG CN

XEWG CN

Nn

R

NaOAcN

n

R

Nn

R

XEWG

NC

−CN−

Nn

R

XEWG

NPh CN

N

BocN

Ph CN

NBn

CNN

N

Ph

NN

Ph NHNPh

N

S

NO

F

N OO

NHAc

ON

94% 95%

90% (6.7:1 r.r.) 72%

61% 79%

58%A. McNally, C. K. Prier, D. W. C. MacMillan, Science, 2011, 334, 1114-1117

α-Amino C-H arylation

Nn

RX

CN

EWG

Ir(ppy)3 (1 mol%)NaOAc (2.0 equiv.)

DMA, 23°C, 12hvisible light (26W CFL)

Nn

R

XEWG

Nn

RIr(ppy)3

*Ir(ppy)3 Ir(ppy)3+

XEWG CN

XEWG CN

Nn

R

NaOAcN

n

R

Nn

R

XEWG

NC

−CN−

Nn

R

XEWG

NPh CN

N

BocN

Ph CN

NBn

CNN

N

Ph

NN

Ph NHNPh

N

S

NO

F

N OO

NHAc

ON

94% 95%

90% (6.7:1 r.r.) 72%

61% 79%

58%A. McNally, C. K. Prier, D. W. C. MacMillan, Science, 2011, 334, 1114-1117

α-Amino C-H arylation

Nn

RX

CN

EWG

Ir(ppy)3 (1 mol%)NaOAc (2.0 equiv.)

DMA, 23°C, 12hvisible light (26W CFL)

Nn

R

XEWG

Nn

RIr(ppy)3

*Ir(ppy)3 Ir(ppy)3+

XEWG CN

XEWG CN

Nn

R

NaOAcN

n

R

Nn

R

XEWG

NC

−CN−

Nn

R

XEWG

NPh CN

N

BocN

Ph CN

NBn

CNN

N

Ph

NN

Ph NHNPh

N

S

NO

F

N OO

NHAc

ON

94% 95%

90% (6.7:1 r.r.) 72%

61% 79%

58%A. McNally, C. K. Prier, D. W. C. MacMillan, Science, 2011, 334, 1114-1117

Trifluoromethylation of Arenes via Direct C-H functionalization

D. A. Nagib, D. W. C. MacMillan, Nature, 2011, 480, 224-228

R

CF3SO2Cl2 (1-4 equiv.)Photocatalyst (1-2 mol%)

K2HPO4, MeCN, 23°Cvisible light

A

C

B

Y

X

RA

C

B

Y

X

CF3

CF3

CF3

R

Ru(phen)32+

*Ru(phen)32+ Ru(phen)33+

S ClF3CO

OS ClF3CO

O

SO2Cl-

CF3

RCF3

CF3H

−H+ CF3R R

N

N

N

N

NH O

N

S

CF3 CF3 CF3

OMe

CF3

OMe

O CF3

CF3

CF3

CF3 Me3Si

OMe

CF3

88% 80% 70%

82% 78% 87%

70% 74% 76%

N OH

OOHOHO

NH

F

4-CF3-Lipitor27%

2-CF3-Lipitor25%

4'-CF3-Lipitor22%

Trifluoromethylation of Arenes via Direct C-H functionalization

D. A. Nagib, D. W. C. MacMillan, Nature, 2011, 480, 224-228

R

CF3SO2Cl2 (1-4 equiv.)Photocatalyst (1-2 mol%)

K2HPO4, MeCN, 23°Cvisible light

A

C

B

Y

X

RA

C

B

Y

X

CF3

CF3

CF3

R

Ru(phen)32+

*Ru(phen)32+ Ru(phen)33+

S ClF3CO

OS ClF3CO

O

SO2Cl-

CF3

RCF3

CF3H

−H+ CF3R R

N

N

N

N

NH O

N

S

CF3 CF3 CF3

OMe

CF3

OMe

O CF3

CF3

CF3

CF3 Me3Si

OMe

CF3

88% 80% 70%

82% 78% 87%

70% 74% 76%

N OH

OOHOHO

NH

F

4-CF3-Lipitor27%

2-CF3-Lipitor25%

4'-CF3-Lipitor22%

Trifluoromethylation of Arenes via Direct C-H functionalization

D. A. Nagib, D. W. C. MacMillan, Nature, 2011, 480, 224-228

R

CF3SO2Cl2 (1-4 equiv.)Photocatalyst (1-2 mol%)

K2HPO4, MeCN, 23°Cvisible light

A

C

B

Y

X

RA

C

B

Y

X

CF3

CF3

CF3

R

Ru(phen)32+

*Ru(phen)32+ Ru(phen)33+

S ClF3CO

OS ClF3CO

O

SO2Cl-

CF3

RCF3

CF3H

−H+ CF3R R

N

N

N

N

NH O

N

S

CF3 CF3 CF3

OMe

CF3

OMe

O CF3

CF3

CF3

CF3 Me3Si

OMe

CF3

88% 80% 70%

82% 78% 87%

70% 74% 76%

N OH

OOHOHO

NH

F

4-CF3-Lipitor27%

2-CF3-Lipitor25%

4'-CF3-Lipitor22%

Trifluoromethylation of Arenes via Direct C-H functionalization

D. A. Nagib, D. W. C. MacMillan, Nature, 2011, 480, 224-228

R

CF3SO2Cl2 (1-4 equiv.)Photocatalyst (1-2 mol%)

K2HPO4, MeCN, 23°Cvisible light

A

C

B

Y

X

RA

C

B

Y

X

CF3

CF3

CF3

R

Ru(phen)32+

*Ru(phen)32+ Ru(phen)33+

S ClF3CO

OS ClF3CO

O

SO2Cl-

CF3

RCF3

CF3H

−H+ CF3R R

N

N

N

N

NH O

N

S

CF3 CF3 CF3

OMe

CF3

OMe

O CF3

CF3

CF3

CF3 Me3Si

OMe

CF3

88% 80% 70%

82% 78% 87%

70% 74% 76%

N OH

OOHOHO

NH

F

4-CF3-Lipitor27%

2-CF3-Lipitor25%

4'-CF3-Lipitor22%

Ru(bpy)32+

*Ru(bpy)32+

Ru(bpy)3+

N

N

MeO

MetBu

Y

FG

N

N+

MeO

MetBu

Y

FGBrFG

FG

O

HY

FG

N

NH

MeO

MetBu

O

HY

N

N

MeO

MetBu

Y

FG

PHOTOREDOX ORGANOCATALYSIS

Merging Photoredox and Organocatalysis: Enantioselective α-Alkylation of Aldehydes

D. A. Nicewicz, D. W. C. MacMillan, Science, 2008, 322, 77-80

H

OY FG Br

R

Ru(bpy)3Cl2 (0.5 mol%)organocatalyst (20 mol%)

2,6-lutidine (2.0 equiv.)

DMF, 23°Cvisible light2.0 equiv.

H

O

YFG

R

H

O

Et

COOEt

COOEt

86%, 90% ee

H

O

COOEt

COOEt

NBoc

66%, 91% ee

H

O

COOEt

COOEt

H

O

Hex

84%, 95% ee

O

NO2

H

O

HexCOOEt

80%, 88% ee

COOEt

H

O

Hex

OCH2CF3

O

80%, 92% ee

Ph

92%, 90% ee

Ru(bpy)32+

*Ru(bpy)32+

Ru(bpy)3+

N

N

MeO

MetBu

Y

FG

N

N+

MeO

MetBu

Y

FGBrFG

FG

O

HY

FG

N

NH

MeO

MetBu

O

HY

N

N

MeO

MetBu

Y

FG

PHOTOREDOX ORGANOCATALYSIS

Merging Photoredox and Organocatalysis: Enantioselective α-Alkylation of Aldehydes

D. A. Nicewicz, D. W. C. MacMillan, Science, 2008, 322, 77-80

H

OY FG Br

R

Ru(bpy)3Cl2 (0.5 mol%)organocatalyst (20 mol%)

2,6-lutidine (2.0 equiv.)

DMF, 23°Cvisible light2.0 equiv.

H

O

YFG

R

H

O

Et

COOEt

COOEt

86%, 90% ee

H

O

COOEt

COOEt

NBoc

66%, 91% ee

H

O

COOEt

COOEt

H

O

Hex

84%, 95% ee

O

NO2

H

O

HexCOOEt

80%, 88% ee

COOEt

H

O

Hex

OCH2CF3

O

80%, 92% ee

Ph

92%, 90% ee

Ru(bpy)32+

*Ru(bpy)32+

Ru(bpy)3+

N

N

MeO

MetBu

Y

FG

N

N+

MeO

MetBu

Y

FGBrFG

FG

O

HY

FG

N

NH

MeO

MetBu

O

HY

N

N

MeO

MetBu

Y

FG

PHOTOREDOX ORGANOCATALYSIS

Merging Photoredox and Organocatalysis: Enantioselective α-Alkylation of Aldehydes

D. A. Nicewicz, D. W. C. MacMillan, Science, 2008, 322, 77-80

H

OY FG Br

R

Ru(bpy)3Cl2 (0.5 mol%)organocatalyst (20 mol%)

2,6-lutidine (2.0 equiv.)

DMF, 23°Cvisible light2.0 equiv.

H

O

YFG

R

H

O

Et

COOEt

COOEt

86%, 90% ee

H

O

COOEt

COOEt

NBoc

66%, 91% ee

H

O

COOEt

COOEt

H

O

Hex

84%, 95% ee

O

NO2

H

O

HexCOOEt

80%, 88% ee

COOEt

H

O

Hex

OCH2CF3

O

80%, 92% ee

Ph

92%, 90% ee

Ru(bpy)32+

*Ru(bpy)32+

Ru(bpy)3+

O

H R

O

HY

PHOTOREDOX ORGANOCATALYSIS

CN

CN

CN

CN

NR

NH

NR

NR

−H+

NR

CN

CN

CN

H2O, −CN−

β-Arylation of Aldehydes and Ketones

M. T. Pirnot, D. A. Rankic, D. B. C. Martin, D. W. C. MacMillan, Science, 2013, 339, 1593-1596

H

OIr(ppy)3 (1.0 mol%)

organocatalyst (20 mol%)DABCO, AcOH

H2O, DMPU, 23°Cvisible light

H

O

R X

CN

EWG

R

X

EWG

NH

HN

H

O

NC

63%

H

O

NBoc

CN

71%

H

O Pent

N

70%

O

tBu CN

70%>20:1 drazepane

O

O

CN

63%piperidine

O

CN82%

55% eecinchona derived

catalyst

Ru(bpy)32+

*Ru(bpy)32+

Ru(bpy)3+

O

H R

O

HY

PHOTOREDOX ORGANOCATALYSIS

CN

CN

CN

CN

NR

NH

NR

NR

−H+

NR

CN

CN

CN

H2O, −CN−

β-Arylation of Aldehydes and Ketones

M. T. Pirnot, D. A. Rankic, D. B. C. Martin, D. W. C. MacMillan, Science, 2013, 339, 1593-1596

H

OIr(ppy)3 (1.0 mol%)

organocatalyst (20 mol%)DABCO, AcOH

H2O, DMPU, 23°Cvisible light

H

O

R X

CN

EWG

R

X

EWG

NH

HN

H

O

NC

63%

H

O

NBoc

CN

71%

H

O Pent

N

70%

O

tBu CN

70%>20:1 drazepane

O

O

CN

63%piperidine

O

CN82%

55% eecinchona derived

catalyst

Ru(bpy)32+

*Ru(bpy)32+

Ru(bpy)3+

O

H R

O

HY

PHOTOREDOX ORGANOCATALYSIS

CN

CN

CN

CN

NR

NH

NR

NR

−H+

NR

CN

CN

CN

H2O, −CN−

β-Arylation of Aldehydes and Ketones

M. T. Pirnot, D. A. Rankic, D. B. C. Martin, D. W. C. MacMillan, Science, 2013, 339, 1593-1596

H

OIr(ppy)3 (1.0 mol%)

organocatalyst (20 mol%)DABCO, AcOH

H2O, DMPU, 23°Cvisible light

H

O

R X

CN

EWG

R

X

EWG

NH

HN

H

O

NC

63%

H

O

NBoc

CN

71%

H

O Pent

N

70%

O

tBu CN

70%>20:1 drazepane

O

O

CN

63%piperidine

O

CN82%

55% eecinchona derived

catalyst

Merging Photoredox and TM catalysis: Coupling of α-carboxyl sp3 carbon with Aryl Halides

Z. Zuo, D. T. Ahneman, L. Chu, J. A. Terrett, A. G. Doyle, D. W. C. MacMillan, Science, 2014, 345, 437-440

NCOOH

R

X

Ir[dF(CF3)ppy]2(dtbbpy)PF6 (1 mol%)NiCl2.glyme (10 mol%)

dtbbpy (15 mol%)

Cs2CO3 (1.5 equiv.), DMF, 48-72 hblue LEDs

NRR

R

1.21 V

0.95 V

-1.2 V

PHOTOREDOX*IrIII

IrIII

IrII LnNiIX

LnNi0LnArNiIIX

NiIIILnAlkX

ArN

COOH

Boc

NBoc

NBoc

XR

NBoc

R

TM

LnNiIIX2

SubstrateIrIII

−H+

−CO2

-1.37 V

-1.7 V

NBoc

OMe

78%from ArI

NBoc

CN

75%from ArBr

NBoc

NF

78%from ArCl

F

N

O

Boc Ac61%

from ArBr

NHBoc

Ac

72%from ArBr

N

NHBoc

AcBoc83%

from ArBr

MeS

NHBoc

AcO

Ac

83%from ArBr

82%from ArBr

N

84%from ArBr

anddimethylaniline

Merging Photoredox and TM catalysis: Coupling of α-carboxyl sp3 carbon with Aryl Halides

Z. Zuo, D. T. Ahneman, L. Chu, J. A. Terrett, A. G. Doyle, D. W. C. MacMillan, Science, 2014, 345, 437-440

NCOOH

R

X

Ir[dF(CF3)ppy]2(dtbbpy)PF6 (1 mol%)NiCl2.glyme (10 mol%)

dtbbpy (15 mol%)

Cs2CO3 (1.5 equiv.), DMF, 48-72 hblue LEDs

NRR

R

1.21 V

0.95 V

-1.2 V

PHOTOREDOX*IrIII

IrIII

IrII LnNiIX

LnNi0LnArNiIIX

NiIIILnAlkX

ArN

COOH

Boc

NBoc

NBoc

XR

NBoc

R

TM

LnNiIIX2

SubstrateIrIII

−H+

−CO2

-1.37 V

-1.7 V

NBoc

OMe

78%from ArI

NBoc

CN

75%from ArBr

NBoc

NF

78%from ArCl

F

N

O

Boc Ac61%

from ArBr

NHBoc

Ac

72%from ArBr

N

NHBoc

AcBoc83%

from ArBr

MeS

NHBoc

AcO

Ac

83%from ArBr

82%from ArBr

N

84%from ArBr

anddimethylaniline

Merging Photoredox and TM catalysis: Coupling of α-carboxyl sp3 carbon with Aryl Halides

Z. Zuo, D. T. Ahneman, L. Chu, J. A. Terrett, A. G. Doyle, D. W. C. MacMillan, Science, 2014, 345, 437-440

NCOOH

R

X

Ir[dF(CF3)ppy]2(dtbbpy)PF6 (1 mol%)NiCl2.glyme (10 mol%)

dtbbpy (15 mol%)

Cs2CO3 (1.5 equiv.), DMF, 48-72 hblue LEDs

NRR

R

1.21 V

0.95 V

-1.2 V

PHOTOREDOX*IrIII

IrIII

IrII LnNiIX

LnNi0LnArNiIIX

NiIIILnAlkX

ArN

COOH

Boc

NBoc

NBoc

XR

NBoc

R

TM

LnNiIIX2

SubstrateIrIII

−H+

−CO2

-1.37 V

-1.7 V

NBoc

OMe

78%from ArI

NBoc

CN

75%from ArBr

NBoc

NF

78%from ArCl

F

N

O

Boc Ac61%

from ArBr

NHBoc

Ac

72%from ArBr

N

NHBoc

AcBoc83%

from ArBr

MeS

NHBoc

AcO

Ac

83%from ArBr

82%from ArBr

N

84%from ArBr

anddimethylaniline

Enantioselective Coupling of α-carboxyl sp3 carbon with Aryl Halides

Z. Zuo, H. Cong, W. Li, J. Choi, G. C. Fu, D. W. C. MacMillan, J. Am. Chem. Soc., 2016, 138, 1832-1835

Photoredox-Assisted Suzuki-type Cross Coupling

J. C. Tellis, D. N. Primer, G. A. Molander, Science, 2014, 345, 433-436

Photoredox-Assisted Suzuki-type Cross Coupling

J. C. Tellis, D. N. Primer, G. A. Molander, Science, 2014, 345, 433-436

Photoredox-Assisted Suzuki-type Cross Coupling

J. C. Tellis, D. N. Primer, G. A. Molander, Science, 2014, 345, 433-436

Photoredox-Assisted Suzuki-type Cross Coupling

J. C. Tellis, D. N. Primer, G. A. Molander, Science, 2014, 345, 433-436

Photoredox-Assisted Hiyama-type Cross Coupling

M. Jouffroy, D. N. Primer, G. A. Molander, J. Am. Chem. Soc., 2016, 138, 475-478

Dual Photoredox and TM

MacMillan, Angew. Chem. Int. Ed., 2015, 54, 7929–7933

MacMillan, Nature, 2015, 524, 330–334

Glorius, J. Am. Chem. Soc., 2013, 135, 5505–5508

Sanford, J. Am. Chem. Soc., 2011, 133,18566–18569

Conclusions

Extremely versitile CC, CN, CO, CP, CB bond formation, FGI… [2+2], [4+2] cycloadditions, oxidative & reductive couplings…

Mild conditions

Room temperature Stable/commercial reagents

Combination with other types of catalysis

Organocatalysis, TM catalysis, HAT Rational design

Catalyst Reaction

Types of catalysts

Cu, Fe, W, … Metal-free: organic dyes

« Organic Photoredox Chemistry » N. A. Romero and D. A. Nicewicz, Chem. Rev., 2016, 16, 10075−10166

Conclusions

Extremely versitile CC, CN, CO, CP, CB bond formation, FGI… [2+2], [4+2] cycloadditions, oxidative & reductive couplings…

Mild conditions

Room temperature Stable/commercial reagents

Combination with other types of catalysis

Organocatalysis, TM catalysis, HAT Rational design

Catalyst Reaction

Types of catalysts

Cu, Fe, W, … Metal-free: organic dyes

« Organic Photoredox Chemistry » N. A. Romero and D. A. Nicewicz, Chem. Rev., 2016, 16, 10075−10166

Conclusions

Extremely versitile CC, CN, CO, CP, CB bond formation, FGI… [2+2], [4+2] cycloadditions, oxidative & reductive couplings…

Mild conditions

Room temperature Stable/commercial reagents

Combination with other types of catalysis

Organocatalysis, TM catalysis, HAT Rational design

Catalyst Reaction

Types of catalysts

Cu, Fe, W, … Metal-free: organic dyes

« Organic Photoredox Chemistry » N. A. Romero and D. A. Nicewicz, Chem. Rev., 2016, 16, 10075−10166

Conclusions

Extremely versitile CC, CN, CO, CP, CB bond formation, FGI… [2+2], [4+2] cycloadditions, oxidative & reductive couplings…

Mild conditions

Room temperature Stable/commercial reagents

Combination with other types of catalysis

Organocatalysis, TM catalysis, HAT Rational design

Catalyst Reaction

Types of catalysts

Cu, Fe, W, … Metal-free: organic dyes

« Organic Photoredox Chemistry » N. A. Romero and D. A. Nicewicz, Chem. Rev., 2016, 16, 10075−10166

Conclusions

Extremely versitile CC, CN, CO, CP, CB bond formation, FGI… [2+2], [4+2] cycloadditions, oxidative & reductive couplings…

Mild conditions

Room temperature Stable/commercial reagents

Combination with other types of catalysis

Organocatalysis, TM catalysis, HAT Rational design

Catalyst Reaction

Types of catalysts

Cu, Fe, W, … Metal-free: organic dyes

« Organic Photoredox Chemistry » N. A. Romero and D. A. Nicewicz, Chem. Rev., 2016, 16, 10075−10166

Conclusions

Extremely versitile CC, CN, CO, CP, CB bond formation, FGI… [2+2], [4+2] cycloadditions, oxidative & reductive couplings…

Mild conditions

Room temperature Stable/commercial reagents

Combination with other types of catalysis

Organocatalysis, TM catalysis, HAT Rational design

Catalyst Reaction

Types of catalysts

Cu, Fe, W, … Metal-free: organic dyes

« Organic Photoredox Chemistry » N. A. Romero and D. A. Nicewicz, Chem. Rev., 2016, 16, 10075−10166